1. Field of the Invention
The present invention relates to a method for driving a liquid crystal display device. In particular, the present invention relates to a driving method of a field-sequential liquid crystal display device.
2. Description of the Related Art
A color filter method and a field sequential method are known as display methods for liquid crystal display devices. In a color-filter liquid crystal display device, a plurality of subpixels which has color filters for transmitting only light with a given wavelength is provided in each pixel. A desired color is produced in such a manner that transmission of white light is controlled in each subpixel and a plurality of colors is mixed in each pixel. In contrast, in a field-sequential liquid crystal display device, a plurality of light sources that emit light of different colors is provided. A desired color is produced in such a manner that lighting of the plurality of light sources is controlled independently and transmission of light of each color is controlled in each pixel. In other words, a desired color is produced by dividing the area of one pixel by lights of given colors in a color filter method, whereas a desired color is produced by dividing a display period by lights of given colors in a field sequential method.
The field-sequential liquid crystal display device has the following advantages over the color-filter liquid crystal display device. First, in the field-sequential liquid crystal display device, it is not necessary to provide subpixels in a pixel. Thus, the aperture ratio can be increased or the number of pixels can be increased. In addition, in the field-sequential liquid crystal display device, it is not necessary to provide a color filter. In other words, light loss caused by light absorption in color filters does not occur. Therefore, transmittance can be improved and power consumption can be reduced.
Patent Document 1 discloses a field-sequential liquid crystal display device. Specifically, Patent Document 1 discloses a liquid crystal display device in which pixels each include a transistor for controlling input of an image signal, a signal storage capacitor for holding the image signal, and a transistor for controlling transfer of electric charge from the signal storage capacitor to a display pixel capacitor. In the liquid crystal display device having this structure, input of an image signal to the signal storage capacitor and display corresponding to electric charge held in the display pixel capacitor can be performed concurrently.